AL3158_11 Datasheet, PDF (1/10 Pages) Diodes Incorporated – HIGH EFFICIENCY 1x/2x CHARGE PUMP FOR WHITE LED APPLICATIONS

AL3158
HIGH EFFICIENCY 1x/2x CHARGE PUMP
FOR WHITE LED APPLICATIONS
Description
Pin Assignments
The AL3158 is a low noise, constant frequency charge pump
DC/DC converter that uses a Dual mode load switch (1x), and (2x)
conversion for white LED applications. The AL3158 is capable of
driving three groups of three LED channels at 20mA from a 2.7V to
5.5V input. The current sinks may be operated using three simple
PWM dimming inputs individually or in parallel for driving higher-
current LEDs. Low external part counts (one 1µF flying capacitor
and two 2.2µF capacitors at V_IN and V_OUT) make this part ideally
suited for small, battery-powered applications.
AL3158 PWM dimming inputs are used to enable, disable device
and dimming LED current with a fixed default current settings at
20mA or other factory programming options available.
Each output of the AL3158 is equipped with built-in protection for
V_OUT short circuit and auto-disable for LED short conditions. Built-in
soft-start circuitry prevents excessive inrush current during start-up
and mode switching. A low-current shutdown feature disconnects
the load from V_IN to reduce quiescent current less than 1µA.
The AL3158 is available in a lead-free, space-saving, thermally
enhanced 20-pin 3 x 3mm QFN package.
Features
Applications
• V_IN Range: 2.7V to 5.5V
• Up to 93% Max Power Efficiency
• 1% Current Matching Accuracy Between Channels
• Three simple PWM dimming for RGB or WLED
• Low transition threshold voltage typical 150 mV
• Dual-Mode 1x and 2x Charge Pump
• Drives up to 3 + 3 + 3 Channels of LEDs
• 1.2 MHz Constant Switching Frequency
• V_OUT short circuit and Thermal Protections
• Soft Start for reducing inrush current
• Under Voltage Lockout Protection
• I_Q <1µA in Shutdown
• Thermally-Enhanced QFN3030-20 Package: Available in “Green”
Molding Compound (No Br, Sb)
• Lead Free Finish/ RoHS Compliant (Note 1)
• Mobile Phone White LED Backlighting and Indicators
• PDA White LED Backlighting
• Battery-operated Phone Main and Sub Screen White LED
Backlighting
Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html
Typical Application Circuit
VIN
8 _VIN
2.2uF
CIN
CP ⁹
CN ⁷
1uF
C1
EN1
EN2
AL3158
VOUT ¹¹
D1
D2
D3
D4
D5
D6
D7 D8
D9
LED
LED
LED
LED
LED LED
LED LED
LED
EN1
EN2
EN3
3 _EN1
5 _EN2
4 _EN3
PGND
6
D1 ¹²
D2 ¹³
D3 ¹⁴
D4 ¹⁵
D5 ¹⁶
D6 ¹⁸
D7 ²⁰
D8 ¹
D9 ²
GND
17
EN3
2.2uF
COUT
AL3158
Document number: DS35047 Rev. 2 - 2
1 of 10
www.diodes.com
January 2011
© Diodes Incorporated